Background/Aims: Each year there are nearly 19 million new sexually transmitted diseases (STDs). STDs cost the U.S. health care system nearly $16 billion each year and incidence rates of STDs have not decreased in recent years. There are very large disparities in the prevalence rates among different races/ethnicities and age groups. We developed a simulation model to assess the potential impact and limitations of screening strategies to prevent the transmission of STDs as a first step in understanding the range of options to curb STD incidence, disparities and costs. Methods: We analyzed the health impact (HI) measured in undiscounted Quality Adjusted Life Years saved QALYs and cost-effectiveness (CE) of separately screening for Chlamydia, gonorrhea and syphilis when offered to the target populations recommended by the USPSTF. We conducted our analysis using an Agent Based Model (ABM) in order to integrate the status of individuals with how they interact with each other. To our knowledge, no previous analysis of screening for these STDs has been conducted using an ABM. An unprecedented contribution of this project is a joint endogeneity of disease transmission, endogenous segregation and relationship dynamics along socioeconomic status (SES). We designed a model structure that allows realistic social networks to emerge based in part on data from well-constructed surveys including the National Survey of Family Growth (NSFG), U.S. Census 2000, the Survey of Income and Program Participation (SIPP), the National Survey of Sexual Health and Behavior (NSSHB) and the National Health and Nutrition Examination Survey (NHANES). Other parameters for the model were obtained from a structured literature search. The agents exhibit assortative behaviors along SES attributes in search of sexual partners and neighborhoods. Results: Chlamydia: HI= 17,000, CE=$27,000/QALY saved. Gonorrhea: HI=8,000, CE=$36,000/QALY saved. Syphilis: HI=5,000, CE=$130/QALY saved. Conclusions: Prevention strategies recommended by the USPSTF are cost-effective. These results provide a direct comparison within a common framework. The ABM framework is general enough to understand the effect of other interventions and other issues, like obesity, substance abuse, teenage pregnancies and other social pathologies, where our environment plays a significant role.